The purpose of this proposal is to illuminate the role that membrane-bound peptides play in the overall regulation of the brain angiotensin system. The proposal utilizes a multidisciplinary approach to investigate this problem and as such includes biochemical, behavioral, electrophysiological, and immunocytochemical studies. Several specific questions related to the overall theme are addressed. These include the following: 1) What is the active form of brain angiotensin? 2) What are the functional and biochemical characteristics of membrane-bound angiotensinases? 3) What are the biochemical characteristics of solubilized and purified angiotensin receptors and are they associated with peptidase activity? 4) Can modifications of peptidase activity alter the response of angiotensin-dependent effector mechanisms? And 5) When angiotensin degradation is blocked, does brain angiotensin turnover reflect the physiological state of the animal?